A1.2 nucleic acids

What is DNA?

Double-stranded molecule storing genetic info.

Where is DNA found?

Nucleus

What are the characteristics of viruses?

Not living (no cells

What is the virus exam tip?

Viruses replicate inside a host cell only.

How are DNA strands linked?

By phosphodiester bonds (5'->3').

What is the structure of the sugar-phosphate backbone?

Provides stability with bases projecting outward

strands are antiparallel.

Where does DNA polymerase add nucleotides?

Only to the 3' end.

Compare DNA vs RNA: Strands

DNA is double-stranded

RNA is single-stranded.

Compare DNA vs RNA: Sugar

DNA has deoxyribose

RNA has ribose.

Compare DNA vs RNA: Bases

DNA has A

RNA has A

U

Compare DNA vs RNA: Role

DNA is for long term storage

RNA is for protein synthesis.

What are codons?

Universal triplet codes for the same amino acid in almost all organisms.

What does the conservation of genetic code reflect?

A shared evolutionary origin.

How is the universal genetic code used in biotechnology?

Allows genes from one species to be expressed in another (e.g.

What are the 3 parts of a nucleotide?

Phosphate (circle)

What explains genetic uniqueness?

Near-infinite variation in base sequences.

How do DNA bases pair and how many H-bonds are formed?

A-T (2 H-bonds) and C-G (3 H-bonds).

How do RNA bases pair?

A-U and C-G.

What defines the genetic code?

The base sequence (codons).

Which bases are purines and which are pyrimidines?

Purines are A and G

Pyrimidines are C

T

Why does a purine always pair with a pyrimidine?

To maintain a constant helix width